1. Field of the Invention
This invention relates to an assembly for mixing and dispensing two liquid components.
2. Description of the Related Art
Static mixing assemblies are in widespread use for storing, mixing and dispensing two liquid components such as two-part curable resins. For example, U.S. Pat. No. 4,538,920 illustrates a syringe having side-by-side barrels for storing different liquid materials, and the syringe includes a detachable exit conduit having a static mixer located downstream of the barrels. As a piston assembly is advanced in the syringe shown in U.S. Pat. No. 4,538,920, liquid materials discharged from the barrels are mixed in the static mixer and dispensed through an outlet of the exit conduit.
A troublesome problem that has been noted in connection with dispensing of certain material from static mixer assemblies is the drippage or drooling of the materials from the exit conduit after the intended end of a dispensing operation. Users of hand-held static mixer assemblies may remove the assembly from the work area to avoid dripping additional mixed materials on the workpiece and place the end of the exit conduit over a disposable cup to catch drips. However, such a procedure represents an annoyance and a waste of materials. Some users have attempted to pull back the handles of the pistons in an attempt to avoid such problems, but it is often observed that relief of pressure in the barrels does not completely stop the drooling of material from the end of the static mixer.
The problem of dripping from static mixers is particularly noticeable when the mixer is part of a stationary dispensing assembly that has an upright orientation. Stationary mixers are often used in automated manufacturing processes, and in these instances care must be taken to insure that the workpiece does not remain beneath the outlet of the static mixer once sufficient amounts of mixed materials have been dispensed. Again such drippage represents a nuisance and an expense that would preferably be avoided.